Abstract
The exact mechanism by which Entamoeba histolytica disrupts the human colonic epithelium and invades the mucosa has yet to be clearly elucidated. E. histolytica produces a diverse array of putative virulent factors such as glycosidase, cysteine proteinases and amebapore that can modulate and/or disrupt epithelial barrier functions. However, it is currently thought that E. histolytica produces numerous other molecules and strategies to disrupt colonic mucosal defenses. In this study, we document a putative mechanism whereby the parasite alters the integrity of human epithelium by expressing a cognate tight junction protein of the host. We detected this protein as "occludin-like" as revealed by immunoblotting and immunoprecipitation studies and visualization by confocal microscopy using antibodies highly specific for human occludin. We propose that E. histolytica occludin-like protein might displace mucosal epithelial occludin-occludin tight junction interactions resulting in epithelial disruption analogous to sub mucosal human dendritic cells sampling luminal contents. These results indicate that E. histolytica occludin is a putative virulent component that can play a role in the pathogenesis of intestinal amebiasis.